Prédiction de la mortalité toutes causes confondues chez les patients en choc cardiogène réfractaire traités par assistance circulatoire percutanée temporaire au CHUV du 1er janvier 2008 au 1er janvier 2017

Introduction Les options thérapeutiques médicamenteuses lors de choc cardiogène réfractaire sont limitées en raison des effets secondaires comme la tachycardie avec augmentation de la consommation en oxygène et la vasoconstriction périphérique. L'oxygénation tissulaire par une assistance de ressuscitation type Extracorporeal Membrane Oxygenation (ECLS) permet de fournir une stabilisation hémodynamique immédiate. Néanmoins, l'amélioration du pronostic vital reste discutée car elle n'a jamais été démontrée par une étude multicentrique randomisée. Cependant, grâce aux études observationnelles favorables, son implantation est considérée comme un standard de prise en charge. Méthodologie Il s’agit d’une étude rétrospective, monocentrique, non randomisée, regroupant 89 patients adultes, qui ont souffert d’un choc cardiogène réfractaire traités par ECLS au CHUV entre le 01.01.20018 et le 01.01.2017. Les paramètres d’évaluation principaux comprennent la mortalité toutes causes confondues, l’implantation d’une LVAD et la transplantation cardiaque ; les secondaires comprennent l’incidence des complications, le SAVE score et l’APACHE II score. Les statistiques ont été réalisées selon les méthodes standards avec une p-value de 0,05. Résultats 89 patients ont pu être inclus dans l’étude, avec un âge moyen de 55.8 ans (± 14,7 ans) dont 61% d’hommes, d’un poids moyen de 83,2 kg (±2,1 kg) pour une taille moyenne de 171 cm (±0.8 cm). Les résultats montrent une survie globale de 40,6% à 1 mois, 35,2% à 6 mois et 32,1% à 1 an. L’étiologie retrouve 38,2% chocs cardiogènes primaires, 32,5% post-cardiotomies, 13,5% « autres », 11,2% posttransplantation et 4,5% post-LVAD. La différence de survie selon l’étiologie n’est pas statistiquement significative avec une p-value à 0,52. Pour les complications : 47.2% hémorragie majeure, 34,8% infections, 30.3% insuffisance rénale aiguë, 28.1% insuffisance hépatique, 21.3% ischémie du membre inférieur, 19.1% complications neurologiques, 10.1% oedème aigu du poumon et 5.6 % complication gastro-intestinale. Une augmentation significative des AVCs avec une p-value à 0,04 entre 20018-2013 et 2014-2016. L’écart de survie entre un APACHE II score < ou > à 20 points est non significatif avec une p-value à 0,34. La différence de survie entre les patients avec une classe de risque II-III ou IV-V selon le Save score est statistiquement significative avec une p-value à 0,04. Conclusion Il n’y a pas d’amélioration de la survie toutes causes confondues avec une survie globale de 40,6% à un mois, de 35,2% à 6 mois et de 32,1% à 1 an. La présence d’une cardiotomie ou d’une implantation de LVAD au préalable, de même que l’étiologie du choc, ne représentent pas des facteurs pronostics statistiquement significatifs avec une p-value à 0,3 et 0,52 respectivement. L’early graft failure est associé au taux de mortalité le plus élevé avec 20% de survivants à 1 mois. L’incidence des complications dans ce collectif est plus élevée que dans la littérature [24] et les AVCs ont augmentés de façon significative en 2014 - 2016, comparativement à 2008 - 2013. Le Save score est un outil plus performant que l’APACHE II score pour prédire la survie avec une p-value à 0,04 montrant une différence de survie statistiquement significative entre les classes de risques II-III et IV-V

Iron-oxides and iron-citrate as new photocatalysts in solar inactivation of Escherichia coli in water:mechanistic aspects

This study addresses the bacterial inactivation mechanism by photo-Fenton process at near-neutral pH, focusing on iron-oxides and iron-citrate as photocatalysts for solar water disinfection and using E. coli as a bacteria model. Cell envelope damage during bacterial inactivation by photo-Fenton and TiO2 photocatalysis were investing providing evidence for lipid peroxidation and cell permeability. TiO2 photocatalysis induced significant cell membrane damage, in contrast to the photo-Fenton process, but the inactivation kinetics for both disinfection processes was similar. A higher efficiency of photo-generation of reactive oxygen species (ROS) in the presence of TiO2 photocatalyst compared with the photo-Fenton system was observed. The bactericidal effect of Fe3+/hv seems possible due to the adsorption of Fe3+ ions on the bacterial cell wall followed by photosensitization of iron-bacteria exciplexes oxidizing the cell membrane. In contrast, the effect of Fe2+/hv was associated with diffusion into the cell giving raise to intracellular dark Fenton¿s reactions. We suggest that cell envelope damage might not necessarily be a unique pathway in bacterial inactivation by photo-Fenton treatment. In particular, the enhancement of an internal (photo)-Fenton process by the synergistic action of UVA and the external Fenton's reactants appears to be an important contribution to bacterial inactivation. Bacterial inactivation by the heterogeneous photo-Fenton process was carried out via iron (hydr)oxide particles, i.e. hematite, goethite, wüstite and magnetite. We found that, the iron (hydr)oxides act as photocatalytic semiconductors and catalysts in the heterogeneous photo-Fenton process with the exception of magnetite, which needs H2O2 as electron acceptors. The Hydroxyl radical and superoxide radical were the principal ROS produced by iron (hydr)oxide particles under light in the absence or presence of H2O2. Natural organic matter (NOM) and inorganic substances did not interfere with the photocatalytic semiconducting action of hematite during bacterial inactivation, but enhanced bacterial inactivation mediated by hematite used as the photo-Fenton reagent. Our results demonstrated, for the first time, that low concentration of iron (hydr)oxides (0.6 mg/L) under sunlight, acting both as semiconductors or catalysts of the heterogeneous photo-Fenton process, may serve as a disinfection method for waterborne bacterial pathogens. Bacterial inactivation by the homogeneous photo-Fenton process was carried out using Fe¿citrate complex as a source of iron. The efficiency of the homogeneous photo-Fenton process using Fe-citrate complex strongly improved bacterial inactivation as compared with the FeSO4 and goethite as sources of iron. The bacterial inactivation rate increased in the order of goethite < FeSO4 < Fe-citrate, which agreed with the ¿OH radicals detected by ESR. Encouraging results were also obtained while applying this treatment for bacterial inactivation in natural water samples at pH 8.5. No bacterial reactivation and/or growth were observed showing that Fe-citrate-based photo-Fenton process efficiently inactivate bacteria using a low iron concentration of Fe-citrate, while avoiding precipitation of ferric hydroxides. The application of the photo-Fenton process at near-neutral pH is a promising technique for bacterial inactivation, due to its simplicity, the use of the sun, the low concentration of reagents and does not produce toxic waste

A Genetic Approach to the Recruitment of PRC2 at the HoxD Locus

Polycomb group (PcG) proteins are essential for the repression of key factors during early development. In Drosophila, the polycomb repressive complexes (PRC) associate with defined polycomb response DNA elements (PREs). In mammals, however, the mechanisms underlying polycomb recruitment at targeted loci are poorly understood. We have used an in vivo approach to identify DNA sequences of importance for the proper recruitment of polycomb proteins at the HoxD locus. We report that various genomic re-arrangements of the gene cluster do not strongly affect PRC2 recruitment and that relatively small polycomb interacting sequences appear necessary and sufficient to confer polycomb recognition and targeting to ectopic loci. In addition, a high GC content, while not sufficient to recruit PRC2, may help its local spreading. We discuss the importance of PRC2 recruitment over Hox gene clusters in embryonic stem cells, for their subsequent coordinated transcriptional activation during development

Reorganisation ofHoxdregulatory landscapes during the evolution of a snake-like body plan

Within land vertebrate species, snakes display extreme variations in their body plan, characterized by the absence of limbs and an elongated morphology. Such a particular interpretation of the basic vertebrate body architecture has often been associated with changes in the function or regulation of Hox genes. Here, we use an interspecies comparative approach to investigate different regulatory aspects at the snake HoxD locus. We report that, unlike in other vertebrates, snake mesoderm-specific enhancers are mostly located within the HoxD cluster itself rather than outside. In addition, despite both the absence of limbs and an altered Hoxd gene regulation in external genitalia, the limb-associated bimodal HoxD chromatin structure is maintained at the snake locus. Finally, we show that snake and mouse orthologous enhancer sequences can display distinct expression specificities. These results show that vertebrate morphological evolution likely involved extensive reorganisation at Hox loci, yet within a generally conserved regulatory framework.Fundação para a Ciência e Tecnologia grant: (PTDB/BEX-BID/0899/2014); Schweizerischer Nationalfonds zur Forderung der Wissenschaftlichen Forschung grant: (310030B_138662); Claraz Foundation; Université de Genève; Instituto Federal de Educação Ciência e Tecnologia do Espírito Santo

Lineage-specific dynamic and pre-established enhancer–promoter contacts cooperate in terminal differentiation

Chromosome conformation is an important feature of metazoan gene regulation; however, enhancer–promoter contact remodeling during cellular differentiation remains poorly understood. To address this, genome-wide promoter capture Hi-C (CHi-C) was performed during epidermal differentiation. Two classes of enhancer–promoter contacts associated with differentiation-induced genes were identified. The first class ('gained') increased in contact strength during differentiation in concert with enhancer acquisition of the H3K27ac activation mark. The second class ('stable') were pre-established in undifferentiated cells, with enhancers constitutively marked by H3K27ac. The stable class was associated with the canonical conformation regulator cohesin, whereas the gained class was not, implying distinct mechanisms of contact formation and regulation. Analysis of stable enhancers identified a new, essential role for a constitutively expressed, lineage-restricted ETS-family transcription factor, EHF, in epidermal differentiation. Furthermore, neither class of contacts was observed in pluripotent cells, suggesting that lineage-specific chromatin structure is established in tissue progenitor cells and is further remodeled in terminal differentiation

5C analysis of the Epidermal Differentiation Complex locus reveals distinct chromatin interaction networks between gene-rich and gene-poor TADs in skin epithelial cells

YesMammalian genomes contain several dozens of large (>0.5 Mbp) lineage-specific gene loci harbouring functionally related genes. However, spatial chromatin folding, organization of the enhancer-promoter networks and their relevance to Topologically Associating Domains (TADs) in these loci remain poorly understood. TADs are principle units of the genome folding and represents the DNA regions within which DNA interacts more frequently and less frequently across the TAD boundary. Here, we used Chromatin Conformation Capture Carbon Copy (5C) technology to characterize spatial chromatin interaction network in the 3.1 Mb Epidermal Differentiation Complex (EDC) locus harbouring 61 functionally related genes that show lineage-specific activation during terminal keratinocyte differentiation in the epidermis. 5C data validated by 3D-FISH demonstrate that the EDC locus is organized into several TADs showing distinct lineage-specific chromatin interaction networks based on their transcription activity and the gene-rich or gene-poor status. Correlation of the 5C results with genome-wide studies for enhancer-specific histone modifications (H3K4me1 and H3K27ac) revealed that the majority of spatial chromatin interactions that involves the gene-rich TADs at the EDC locus in keratinocytes include both intra- and inter-TAD interaction networks, connecting gene promoters and enhancers. Compared to thymocytes in which the EDC locus is mostly transcriptionally inactive, these interactions were found to be keratinocyte-specific. In keratinocytes, the promoter-enhancer anchoring regions in the gene-rich transcriptionally active TADs are enriched for the binding of chromatin architectural proteins CTCF, Rad21 and chromatin remodeler Brg1. In contrast to gene-rich TADs, gene-poor TADs show preferential spatial contacts with each other, do not contain active enhancers and show decreased binding of CTCF, Rad21 and Brg1 in keratinocytes. Thus, spatial interactions between gene promoters and enhancers at the multi-TAD EDC locus in skin epithelial cells are cell type-specific and involve extensive contacts within TADs as well as between different gene-rich TADs, forming the framework for lineage-specific transcription.This study was supported by the grants 5R01AR064580 and 1RO1AR071727 to VAB, TKS and AAS, as well as by the grants from MRC (MR/ M010015/1) and BBSRC (BB/K010050/1) to VAB